Abstract (Alk-1-ynyl) chlorocarbenes (3), generated from 1, 1-dihaloalk-2-ynes and 3- substituted 3-bromo-1, 1, 1-trichloropropanes under the action of Bu t OK in THF at 20° C, react with excess alkali metal alkoxide 4 to give 3-substituted 2-(alk-1-ynyl) oxiranes (6) in
